This is the Account Controller Class for Our Application

AccountController.cs

using System;
using System.Collections.Generic;
using System.IdentityModel.Tokens.Jwt;
using System.Linq;
using System.Security.Claims;
using System.Text;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Options;
using Microsoft.IdentityModel.Tokens;
using NG_Core_Auth.Helpers;
using NG_Core_Auth.Models;

// For more information on enabling Web API for empty projects, visit https://go.microsoft.com/fwlink/?LinkID=397860

namespace NG_Core_Auth.Controllers
{
    [Route("api/[controller]")]
    public class AccountController : Controller
    {

        private readonly UserManager<IdentityUser> _userManager;

        private readonly SignInManager<IdentityUser> _signManager;

        private readonly AppSettings _appSettings;


        public AccountController(UserManager<IdentityUser> userManager, SignInManager<IdentityUser> signInManager,  IOptions<AppSettings> appSettings)
        {
            _userManager = userManager;
            _signManager = signInManager;
            _appSettings = appSettings.Value;

        }


       [HttpPost("action")]
        public async Task<IActionResult> Register([FromBody] RegisterViewModel formdata) 
        {
            // Will hold all the errors related to registration
            List<string> errorList = new List<string>();

            var user = new IdentityUser
            {
                Email = formdata.Email,
                UserName = formdata.UserName,
                SecurityStamp = Guid.NewGuid().ToString()
            };

            var result = await _userManager.CreateAsync(user, formdata.Password);

            if (result.Succeeded)
            {
                await _userManager.AddToRoleAsync(user, "Customer");

                // Sending Confirmation Email

                return Ok(new {username = user.UserName, email = user.Email, status = 1, message = "Registration Successful" });

            }
            else 
            {
                foreach (var error in result.Errors)
                {
                    ModelState.AddModelError("", error.Description);
                    errorList.Add(error.Description);
                }
            }

            return BadRequest(new JsonResult(errorList));

        }

        // Login Method
        [HttpPost("action")]
        public async Task<IActionResult> Login([FromBody] LoginViewModel formdata) 
        {
            // Get the User from Database
            var user = await _userManager.FindByNameAsync(formdata.Username);

            var roles = await _userManager.GetRolesAsync(user);

            var key = new SymmetricSecurityKey(Encoding.ASCII.GetBytes(_appSettings.Secret));

            double tokenExpiryTime = Convert.ToDouble(_appSettings.ExpireTime);

            if (user != null &&  await _userManager.CheckPasswordAsync(user, formdata.Password))
            {
                // Confirmation of email
                var tokenHandler = new JwtSecurityTokenHandler();

                var tokenDescriptor = new SecurityTokenDescriptor
                {
                    Subject = new ClaimsIdentity(new Claim[]
                    {
                        new Claim(JwtRegisteredClaimNames.Sub, formdata.Username),
                        new Claim(JwtRegisteredClaimNames.Jti, Guid.NewGuid().ToString()),
                        new Claim(ClaimTypes.NameIdentifier, user.Id),
                        new Claim(ClaimTypes.Role, roles.FirstOrDefault()),
                        new Claim("LoggedOn", DateTime.Now.ToString()),

                     }),

                    SigningCredentials = new SigningCredentials(key, SecurityAlgorithms.HmacSha256Signature),
                    Issuer = _appSettings.Site,
                    Audience = _appSettings.Audience,
                    Expires = DateTime.UtcNow.AddMinutes(tokenExpiryTime)
                };

                // Generate Token

                var token = tokenHandler.CreateToken(tokenDescriptor);

                return Ok(new {token = tokenHandler.WriteToken(token), expiration = token.ValidTo, username = user.UserName, userRole = roles.FirstOrDefault() });

            }

            // return error
            ModelState.AddModelError("", "Username/Password was not Found");
            return Unauthorized(new { LoginError = "Please Check the Login Credentials - Ivalid Username/Password was entered" });

        }




    }
}